Pressure sensitive adhesives (PSAs) have gained wide spread acceptance in many applications. These adhesives are characterized by being normally tacky at room temperature (e.g., 20.degree. C.) and forming a bond to a surface by the application of, at most, very light finger pressure. They possess a balance of viscoelastic and elastic properties which result in a four-fold balance of adhesion, cohesion, stretchiness and elasticity. They have sufficient cohesiveness and elasticity so that they can be handled and removed from surfaces without leaving a residue even though they are tacky. PSAs do not embrace compositions merely because they are sticky or adhere to a surface.
Microparticle-containing PSAs represent one category of PSAs. This category of PSAs contains a plurality of microparticles which may or may not be inherently pressure sensitive and may or may not be hollow. Microparticle-containing PSAs may also include a binder to assist in securing the particles to a substrate. The binder may be inherently pressure sensitive if desired. Examples of these PSAs are disclosed in the art. For example, see U.S. Pat. No. 3,857,731 (Merrill et al), U.S. Pat. No. 4,656,218 (Kinoshita), U.S. Pat. No. 4,735,837 (Miyasaka et al), U.S. Pat. No. 4,855,170 (Darvall et al), U.S. Pat. No. 4,994,322 (Delgado et al), U.S. Pat. No. 5,118,750 (Silver et al), and WO 93/02855 (Mallya et al). The adhesives disclosed in these references are not water-dispersible. They agglomerate and form tacky globules when attempts are made to repulp them. The globules, commonly referred to as "stickles" in the art, plug screens used in the repulping process and lead to increased manufacturing time and expense. Additionally, any globules that are not removed by screening adversely affect the quality of the paper product resulting from such recycling efforts. As a result a need exists for a water-dispersible pressure sensitive microparticle adhesive that can be readily repulped.